System and method for circuits to allow CPAP to provide zero pressure

ABSTRACT

A system comprises a respiratory delivery arrangement adapted to cover at least one respiratory orifice of a patient. The system also comprises a first conduit having a first end and a second end, the second end connected to the respiratory delivery arrangement. A positive pressure is provided to the respiratory orifice via the first conduit and a second conduit having a third end and a fourth end, the fourth end connected to the respiratory delivery arrangement. An exhaled gas is extracted from the respiratory orifice by one or both of a valve configured to redirect flow through the respiratory delivery arrangement and a venturi opening.

PRIORITY CLAIM

The present application claims priority to U.S. Provisional ApplicationSer. No. 61/172,413 entitled “Circuits to Allow CPAP to Provide ZeroPressure” filed on Apr. 24, 2009, the entire disclosure of which isincorporated herein by reference.

BACKGROUND INFORMATION

Noninvasive CPAP procedures have come into widespread use for thetreatment of sleep apnea and during episodes of acute and chronicrespiratory failure without using endotracheal intubation. All forms ofsuch non-invasive positive pressure ventilation (PPV) procedures requirethat a mask be worn over a respiratory orifice of a patient to providean interface with a source of positive pressure. A leak port is providedon the mask to vent exhaled CO2 from the system. Current CPAP technologyrelies on a predetermined low pressure of greater than approximately 3-5cm H₂O to vent exhaled gas out of the leak port during exhalation.However, when a positive pressure supplied by a pressurized air sourcefalls below this value, venting through the leak port ceases, thuscausing a buildup of exhaled CO₂ within the mask.

SUMMARY OF THE INVENTION

The present invention is directed to systems and method for providingventilation to a respiratory delivery system when a positive pressurebeing supplied by a respiratory device falls below a threshold value. Inone respect, the present invention is directed to a system comprising arespiratory delivery arrangement adapted to cover at least onerespiratory orifice of a patient. The system comprises a leak portlocated adjacent to the respiratory delivery arrangement and firstconduit having a first end and a second end, the second end connected tothe respiratory delivery arrangement, a positive pressure being providedto the respiratory orifice via the first conduit and a second conduithaving a third end and a fourth end, the third end being separated fromthe first end, the fourth end connected to the respiratory deliveryarrangement. The system also comprises a valve located in the firstconduit and having a first position and a second position, wherein whenthe valve is in the first position, (a) a positive pressure flowsthrough the first and second conduits and (b) exhaled gas from therespiratory orifice exits the leak port, and wherein, when the valve isin the second position, (c) a positive pressure flows through only thesecond conduit and (d) exhaled gas from the respiratory orifice exitsthe leak port and through the valve.

In another respect, the present invention is directed to a systemcomprising a respiratory delivery arrangement adapted to cover at leastone respiratory orifice of a patient. The system comprises leak portlocated at or near the respiratory orifice. The system also comprises afirst conduit having a first end, a second end, and a first valve, thefirst valve having a first position and second position, the second endconnected to the respiratory delivery arrangement, a positive pressurebeing provided to the respiratory orifice via the first conduit. Thesystem also comprises a second conduit located within the first conduitand having a third end, a fourth end and a venturi opening entraininggas from the third end to the ambient environment, the third end beingseparated from the first end, the fourth end connected to therespiratory delivery arrangement. When the first valve is in the firstposition, (a) a positive pressure flows through the first conduit and(b) a first portion of exhaled gas from the respiratory orifice exitsthe leak port and wherein, when the first valve is in the secondposition, (a) positive pressure flow through the first conduit isprevented, (b) an inhalation gas is drawn in from the opening via thefirst conduit, (c) a first portion of exhaled gas from the respiratoryorifice exits the leak port and (d) a second portion of exhaled gasexits the venturi opening via the second conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first exemplary embodiment of a system according to thepresent invention; and

FIG. 2 shows a second exemplary embodiment of a system according to thepresent invention.

DETAILED DESCRIPTION

The present invention may be further understood with reference to thefollowing description and the appended drawings, wherein like elementsare referred to with the same reference numerals. The present inventionis directed to a system and method for ventilating a CPAP system when apositive pressure being supplied by a CPAP blower falls below apredetermined threshold of approximately 3-5 cm H₂O and, morespecifically, when a positive pressure is at or close to zero. Theexemplary embodiments of the present invention are directed to systemsand methods that provide for an automatic adjustment of the CPAP deviceto the lowered positive pressure so that a venting of exhaled gases ispermitted without any manual effort on the part of a wearer. It is notedthat although embodiments of the present invention are described withrespect to CPAP procedures, the present invention may be employed forthe treatment of any respiratory conditions where a mask is used toadminister an airway pressure including treatments for sleep apnea,hypopnea, snoring, somnolence, etc. without deviating from the spiritand scope of the present invention. As described herein, the termproximal refers to a direction approaching a CPAP device and the termdistal refers to a direction approaching a respiratory mask worn over arespiratory orifice on a head of a patient.

As will be described in greater detail hereinafter, the exemplary systemof the present invention is configured to prevent a buildup of exhaledgases within a CPAP system, which can be potentially harmful to a wearerof the system.

FIG. 1 shows a system 100 according to a first exemplary embodiment ofthe present invention. The system 100 comprises a CPAP blower 102configured to provide pressurized air to a patient via a first conduit110. The CPAP blower 102 is connected to a computer 106 configured tocontrol the flow of pressurized air through the system 100, as thoseskilled in the art will understand. The first conduit 110 extends from aproximal end 112 connected to the CPAP blower 102 to a distal end 114connected to a respiratory mask 104 covering a respiratory orifice(e.g., nasal cavity or oral cavity) of a patient (not shown). A leakport 122 is located on the respiratory mask 104 to provide a continuousexit of exhaled gas from the system 100 when a pressure therein isgreater than approximately 3-5 cm H₂O. It is noted that although theleak port 122 is shown on the mask 104 of the present invention, theleak port 122 may also be positioned elsewhere on the system 100 at alocation that is substantially adjacent to the respiratory orifice ofthe patient. The first conduit 110 is formed of a substantially flexibleand durable material known in the art and is dimensioned to permit apredetermined volume of air therethrough at a predetermined pressure, asthose skilled in the art will understand. The system 100 also comprisesa second conduit 116 open to the mask 104. The second conduit 116extends from a proximal end 118 open to a proximal portion of the firstconduit and the CPAP blower 102 to a distal end open to the mask 104. Aswill be described in greater detail below, the device 100 of the presentinvention is configured to bypass a need for a suctioning device to drawexhaled gas out of the system. It is noted however, that an optionalsuctioning device may be incorporated in the system 100 withoutdeviating from the spirit and scope of the present invention. It isfurther noted that although the second conduit 116 is shown to extendthrough the first conduit 110, the second conduit 116 may alternativelyassume any position relative thereto as long as the distal end 120 opensinto the mask 104 and provides a means for exhaled gas from therespiratory orifice to be removed independently of a pressure in themask 104. For example, in a first alternate embodiment, the secondconduit 116 may be located externally of the first conduit 110 as longas the proximal and distal ends 118, 120 are fluidly connected to theCPAP blower 102 and mask 104, respectively.

The system 100 also comprises a valve 108 configured to selectively sealan opening 109 located adjacent thereto. The valve 108 is a two-wayvalve located substantially adjacent the proximal end 112 of the firstconduit 110. The valve 108 is connected to the computer 106 via one of awired and a wireless connection. Thus, the computer 106 canautomatically move the valve 108 from a first position to a secondposition when a predetermined condition is met, as will be described ingreater detail hereinafter. In a first position, the valve 108 isconfigured to fluidly seal the opening 109 while leaving the firstconduit 110 substantially unobstructed so that air can flowtherethrough. In a second position, the valve 108 is moved so that thefirst conduit 110 is substantially sealed to airflow. Specifically,movement of the valve 108 to the second position fluidly seals aproximal portion 110′ of the first conduit 110 located proximally of thevalve 108 with respect to a distal portion 110″ located distallythereof. In the second position, the opening 109 is fluidly connected tothe distal portion 110″ so that the distal portions 110″ is open to theatmosphere, as will be described in greater detail hereinafter.

In accordance with an exemplary method of the system 100, the proximalend 112 of the first conduit 110 is connected to the CPAP blower 102 andthe distal end 114 to the respiratory mask 104. When the valve 108 is inthe first position (i.e., when a positive air pressure exceeding apredetermined limit is being supplied), the first and second conduits110, 116 remain unobstructed and positive air is guided through each ofthe first and second conduits 110, 116 in the directions A and B,respectively. Exhaled gas from the patient is then guided out of thesystem 100 via the leak port 122 located on the mask 104. In anexemplary embodiment, the valve 108 remains in the first operativeposition as long as the positive air supply has a pressure greater than5 cm. H₂O, wherein the pressure is selected based on the breathingparameters of the patient, as those skilled in the art will understand.It is noted that the system 100 may further comprise a sensor 115located in any of the components thereof to monitor pressure and/orflow, as those skilled in the art will understand.

When the pressure of the positive air supply falls below 5 cm. H₂O, thevalve 108 moves to the second position. Movement of the valve 108 to thesecond operative position ensures that exhaled CO₂ is properlyventilated from the system 100. Specifically, in the second position,the first conduit 110 is sealed to airflow such that positive airflow isonly permitted in the direction B through the second conduit 116. Thesecond conduit 116 is sized and shaped so that air flow therethrough hasa pressure of approximately 25 l/min. Exhaled CO₂ from the respiratoryorifice of the patient then travels in the direction C to exit the leakport 122. Furthermore, the exemplary embodiment of the present inventionalso guides the exhaled CO₂ in the direction D through the first conduit110 and out of the opening 109. Thus, whereas present CPAP devices wouldprevent a leakage of CO₂ at low pressure, the exemplary embodiment ofFIG. 1 facilitates venting of CO₂ from the system 100 when the airpressure in the system 100 falls below a predetermined parameter. Thevalve 108 remains in the second position until a CPAP air pressure onceagain exceeds 5 cm. H₂O (e.g., when the patient returns to a sleepingstate, etc.).

In another embodiment of the present invention, the valve 108 of thesystem 100 may shift between the first and second positions upon receiptof a signal from the sensor 115 provided in the system 100.Specifically, as those skilled in the art will understand, the sensormay be provided within one of the mask 104 or in the distal portion 110″of the first conduit 110 located distally of the valve 108, the sensor115 being configured to measure the patient's breathing patterns andmake a determination of whether the patient is in a sleep state or anawake state. As those skilled in the art will understand, the sensor 115may be positioned anywhere within the system 100 so that the sensor 115is provided with data corresponding to a patient's breathing patternsregardless of a position of the valve 108. The sensor 115 may beconnected to a database containing data corresponding to breathingpatterns indicative of each of the two states. The database may becompiled with data from the patient or from a plurality of testsubjects, as those skilled in the art will understand. The valve 108 maythen be configured to remain in the first position when the patient isin the sleep state. As described in greater detail earlier, in the firstposition, the opening 109 may be sealed so that a positive air flowstravels in the directions A, B and the leak port 122 permits exhaled gasto leave the system 100. When the sensor 115 indicates that the patienthas awakened, the valve 108 may move to the second position so that theopening 109 is open to the environment. Movement of the valve 108 fromthe first position to the second position then prevents air flow fromthe CPAP blower to travel through the first conduit 110 to the patient,as described in greater detail earlier.

FIG. 2 depicts a system 200 according to an alternate embodiment of thepresent invention. The system 200 is formed substantially similarly asthe system 100 of FIG. 1 with the exception of an additional venturiopening 211 provided therein. Specifically, the system 200 comprises afirst conduit 210 extending from a proximal end 212 connected to theCPAP blower 102 to a distal end 214 connected to a respiratory mask 204covering a respiratory orifice (e.g., nasal cavity or oral cavity) of apatient (not shown). The mask 204 comprises a leak port 222 configuredto facilitate the flow of exhaled CO₂ out of the system 200. However, aswill be described in greater detail below, the leak port 222 is optionalonly and may be omitted without deviating from the spirit and scope ofthe invention. The system 200 also comprises a second conduit 216located within the first conduit 210. The second conduit 216 extendsfrom a proximal end 218 to a distal end 220 open to the mask 204. Theventuri opening 211 is formed as an opening on a wall of the firstconduit 210 and, according to one embodiment of the present invention,is open to both the first and second conduits 210, 216. The exemplaryembodiment of the present invention is configured so that when there isa low pressure within the system 200, the venturi opening 211 remainsopen to an ambient environment to permit entrained gas to exittherefrom. Specifically, since the proximal end 218 of the secondconduit 216 is located adjacent the venturi opening 211, a flow ofentrained gas through the second conduit 216 is sufficient to cause theventuri opening 211 to permit flow therethrough, as those skilled in theart will understand.

The valve 208 is a two-way valve formed substantially similarly as thevalve 108. Specifically, the valve 208 is connected to the computer 106via one of a wired and a wireless connection. In a first position, thevalve 208 is configured to fluidly seal an opening 209 while leaving thefirst conduit 210 substantially unobstructed. In a second position, thevalve 208 separates the first conduit 210 into proximal and distalportions 210′, 210″ and opens the opening 209 to the atmosphere, asdescribed in greater detail earlier.

In accordance with an exemplary method for the system 200, the proximalend 212 of the first conduit 210 is connected to the CPAP blower 102 andthe distal end 214 to the respiratory mask 204. When a positive airsupply being supplied to the system 200 exceeds a predeterminedthreshold value, the valve 208 is in the first position. In thisconfiguration, the positive air supply is directed through the firstconduit 210 in the direction E. Exhaled gas from the respiratory orificeof the patient can exit the system 200 from the leak port 222 in thedirection F. In one embodiment of the present invention, the venturiopening 211 may remain open when the positive air supply is beingsupplied. Thus, exhaled gas from the respiratory orifice may also flowproximally from the distal opening of the second conduit 216 and out ofthe venturi opening 211 in the direction G. It is therefore noted that,in an alternate embodiment of the invention, the leak port 222 may beomitted from the system 200 without affecting the principle of operationthereof. Specifically, the positive pressure within the system 200 maycause suction at the venturi opening 211, thus forcing a movement of gasin the direction G through the second conduit 216 and out of the venturiopening 211. However, it is submitted that this is not a requiredcomponent of the present invention and that, in another exemplaryembodiment, the venturi opening 211 may remain closed when positive airwith a pressure above the predetermined threshold is being supplied tothe system. Specifically, the system 200 may be provided with a blockingmeans (e.g., a valve, a plug, etc.) configured to prevent flow throughthe venturi opening 211 when the valve 208 is in the first position. Theblocking means (not shown) may be removed from the venturi opening 211when the valve 208 is moved to the second position, wherein a pressureof expiratory flow through the second conduit 216 may open the venturiopening 211 to permit flow thereoutof, as those skilled in the art willunderstand and as described in greater detail hereinafter. In anexemplary embodiment, the valve 208 remains in the first position aslong as the positive air supply has a pressure greater thanapproximately 5 cm. H₂O.

When the positive air pressure falls below 5 cm. H₂O, the valve 208moves to the second position. In this position, positive pressure E fromthe CPAP blower is prevented from entering either the first or secondconduits 210, 216. Rather, the valve 208 opens the opening 209 so thatatmospheric air is permitted to flow into the distal portion 210″ of thefirst conduit 210 in the direction H. The movement of exhaled gasthrough the system 200 follows the same pattern as described in thefirst valve position wherein a first portion of exhaled gas from therespiratory orifice exits the leak port 222 in the direction F and asecond portion of the exhaled gas is guided through the second conduit216 and out of the venturi opening 211 in the direction G. Specifically,the venturi opening 211 causes a suction to be applied adjacent thereto,the suction force drawings the exhaled gas proximally from the distalend 220 of the second conduit 216 and out of the venturi opening 211.The valve 208 remains in the second operative configuration until a CPAPair pressure E once again exceeds 5 cm. H₂O (e.g., when the patientreturns to a sleeping state, etc.). This exemplary embodiment thus usesa valve 208 and a venturi opening 211 in combination to guide both theflow of positive and negative air through the system 200.

It is noted that various modifications may be made to the embodimentsdisclosed herein without deviating from the scope of the presentinvention. For example, although the present invention has beendescribed with a venturi opening 211, another gas withdrawal means maybe provided on the system 200. In one such exemplary embodiment, suctioncan be provided to the system 200 by a suction device or anothersuctioning means, as those skilled in the art will understand.

While specific embodiments of the invention have been illustrated anddescribed herein, it is realized that numerous modifications and changeswill occur to those skilled in the art. It is therefore to be understoodthat the appended claims are intended to cover all such modificationsand changes as fall within the true spirit and scope of the invention.

1. A system, comprising: a respiratory delivery arrangement adapted tocover at least one respiratory orifice of a patient, the respiratorydelivery arrangement comprising a leak port; a first conduit having afirst end and a second end, the second end connected to the respiratorydelivery arrangement, a positive pressure being provided to therespiratory orifice via the first conduit; a second conduit having athird end and a fourth end, the third end being separated from the firstend, the fourth end connected to the respiratory delivery arrangement;and a valve located in the first conduit, the valve having a firstposition and a second position, wherein when the valve is in the firstposition, (a) a positive pressure flows through the first and secondconduits and (b) exhaled gas from the respiratory orifice exits throughthe leak port, wherein, when the valve is in the second position, (a) apositive pressure flows through only the second conduit, (b) a firstportion of exhaled gas from the respiratory orifice exits the leak portand (c) a second portion of exhaled gas exits through the valve.
 2. Thesystem of claim 1, wherein the first end is coupled to a respiratorydevice providing the positive pressure.
 3. The system of claim 1,wherein the valve moves to the second position when a flow of positivepressure falls below a predetermined flow rate.
 4. The system of claim3, wherein the predetermined flow rate is 5 cm H₂O.
 5. The system ofclaim 1, wherein, when the valve is in the second position, an openingformed adjacent the valve is open to an ambient atmosphere.
 6. Thesystem of claim 1, wherein the second conduit is located within thefirst conduit.
 7. The system of claim 1, wherein the second conduitextends external to and parallel to the first conduit.
 8. The system ofclaim 1, wherein the valve is controlled by feedback from a sensorlocated in the respiratory delivery arrangement.
 9. The system of claim8, wherein the sensor is configured to determined whether the patient isin one of an awake state and a sleep state.
 10. The system of claim 9,wherein the valve moves to the second position when the sensor indicatedthat the patient is in the awake state.
 11. The system of claim 9,wherein the valve prevents positive pressure flow through the first andsecond conduits in the awake state.
 12. A system, comprising: arespiratory delivery arrangement adapted to cover at least onerespiratory orifice of a patient; a first conduit having a first end, asecond end, and a valve, the valve having a first position and secondposition, the second end connected to the respiratory deliveryarrangement, a positive pressure being provided to the respiratoryorifice via the first conduit; a second conduit located within the firstconduit and having a third end, a fourth end and a venturi opening, thethird end being separated from the first end, the fourth end connectedto the respiratory delivery arrangement; and wherein, when the valve isin the first position, (a) a positive pressure flows through the firstconduit and (b) a first portion of exhaled gas from the respiratoryorifice is guided through the second conduit to exit through the venturiopening, and wherein, when the valve is in the second position, (a)positive pressure flow from the first conduit is prevented, (b)inhalation gas is drawn in from an ambient atmosphere via the firstconduit, and (c) a first portion of exhaled gas from the respiratoryorifice is guided through the second conduit to exit through the venturiopening.
 13. The system of claim 12, wherein the first end is coupled toa respiratory device providing the positive pressure.
 14. The system ofclaim 12, wherein when the valve is in the first position, a secondportion of exhaled gas from the respiratory orifice exits through a leakport provided in the respiratory arrangement and when the valve is inthe second position, a second portion of exhaled gas from therespiratory orifice exits through the leak port.
 15. The system of claim12, wherein, when the valve is in the second position, an openinglocated adjacent the valve is open to the ambient atmosphere.
 16. Thesystem of claim 12, wherein the valve is controlled by feedback from asensor located in the respiratory delivery arrangement.
 17. A method,comprising: positioning a respiratory delivery arrangement over at leastone respiratory orifice of a patient, the respiratory deliveryarrangement comprising a leak port, a first conduit having a first endand a second end, the second end connected to the respiratory deliveryarrangement, a positive pressure being provided to the respiratoryorifice via the first conduit, a second conduit having a third end and afourth end, the third end being separated from the first end, the fourthend connected to the respiratory delivery arrangement and a valvelocated in the first conduit, the valve having a first position and asecond position; monitoring data corresponding to a breathing pattern ofa patient; supplying, based on the breathing pattern, a predeterminedpressure of air to the patient; and controlling the valve so that whenthe air pressure is within a first range, the valve is moved to thefirst position and (a) a positive pressure flows through the first andsecond conduits and (b) exhaled gas from the respiratory orifice exitsthrough the leak port and, when the air pressure is within a secondrange, the valve is moved to the second position and (a) a positivepressure flows through only the second conduit, (b) a first portion ofexhaled gas from the respiratory orifice exits the leak port and (c) asecond portion of exhaled gas exits through the valve.
 18. The method ofclaim 17, wherein the valve is controlled by feedback from a sensorlocated in the respiratory delivery arrangement.
 19. A method,comprising: positioning a respiratory delivery arrangement over at leastone respiratory orifice of a patient, the respiratory deliveryarrangement comprising a first conduit having a first end, a second end,and a valve, the valve having a first position and second position, thesecond end connected to the respiratory delivery arrangement, a positivepressure being provided to the respiratory orifice via the first conduitand a second conduit located within the first conduit and having a thirdend, a fourth end and a venturi opening, the third end being separatedfrom the first end, the fourth end connected to the respiratory deliveryarrangement; monitoring data corresponding to a breathing pattern of apatient; supplying, based on the breathing pattern, a predeterminedpressure of air to the patient; and controlling the valve so that whenthe air pressure is within a first range, the valve is moved to thefirst position and (a) a positive pressure flows through the firstconduit and (b) a first portion of exhaled gas from the respiratoryorifice is guided through the second conduit to exit through the venturiopening and, when the air pressure is within a second range, the valveis moved to the second position and (a) positive pressure flow from thefirst conduit is prevented, (b) inhalation gas is drawn in from anambient atmosphere via the first conduit, and (c) a first portion ofexhaled gas from the respiratory orifice is guided through the secondconduit to exit through the venturi opening.
 20. The method of claim 19,wherein the valve is controlled by feedback from a sensor located in therespiratory delivery arrangement.